Spare Tire for Cadillac CTS

I own a 2009 Cadillac CTS Coupe, which I purchased new. As delivered, while the trunk has a well to accommodate a donut spare, the car comes equipped with a compressor/sealer for repairing a flat tire on the road.

If I ever experienced a serious tire failure that the compressor could not fix, the car would require a tow, and couldn’t be driven without a new tire. I also suspect the compressor would only be a temporary fix, and I would need to replace the tire ASAP.

I could get a full-sized spare, but it would occupy almost my entire trunk. I might find an after-market donut (obviously need to match the lug pattern), but I suspect this could be a problem. The car normally operates as two-wheel drive (rear wheels), but automatically switches to 4-wheel drive if it senses wheel slip. If I installed a donut, given that tire’s much smaller diameter, would the car interpret this as wheel slip, causing the drive train to try to switch into 4-wheel mode? I suspect this would mess up the handling and put strain on the drive train. My guess is that Cadillac doesn’t provide a donut because the car can’t be driven safely with one. Is this true, or will a donut work in an emergency?

Auto manufacturers have been trying to ditch the spare tire for years. Over 50 years ago, the Rambler 9 passenger station wagon had no place for a spare tire, so it cme with what were called captive air tires. I guess you have to just live with the car the way it came.

Triedaq – appreciate your reply. I’m well-aware of the desire to “ditch” the spare tire. They’re rarely used, but take up a lot of space and are expensive to provide. Hence, the “compact spare” or donut, which is much smaller and cheaper, and will allow the car to be driven a relatively short distance at low speed until the failed tire can be repaired or replaced. However, I got neither with my Caddy. In fact, I suspect the compressor/sealer unit, which is powered from the car’s 12V battery, is more expensive than a donut. My guess is that a donut causes drive-train problems with this car. That’s what I’d like to try to get confirmed.

I’m a little confused. If they put a well in the trunk, wouldn’t that mean they also had a spare available to fit in there? Have you asked a Cadillac parts department about that?

Apparently other owners share your displeasure. Cadillac offers a compact spare as an option for 2011. It might fit your car, too. Talk to the parts department if you want a compact spare. If you want a full size spare, buy a matching rim, one tire, and have it mounted.

At my dealer’s suggestion when I first brought up the issue of a spare of some sort (soon after I purchased the car), they suggested I check back with them from time-to-time to see if Cadillac would offer a spare for this car. I followed their suggestion, and “checked-back” as recently as yesterday. I was told by the dealer’s parts manager that Cadillac still doesn’t offer a spare tire for this car, and likely never will. jsanders indicated that Cadillac has an option for a compact spare on the 2011 model. I’ll need to follow up on that, because the parts guy at Cadillac stated that they didn’t have a spare for the 2010 or 2011 models either. As far as the well in the truck, my suspicion, and it’s only that, is that the body designers didn’t talk with the drive-train engineers, so after the car was designed to accommodate a compact spare, the engineers decided that the car could not be driven with one, so the compressor was substituted, but the well in the trunk remains. Again, that’s only my guess. I’m trying to confirm whether or not such is truly the case that the car should not be driven with a compact spare due to handling and drive-train concerns.

In 2008, Cad CTS had a compact spare, jack etc. available for about $300. Regarding its use on your car, check to see what the owner’s manual says and ask your dealer. If he does not know, there is nothing to prevent him from asking Cadillac.

We also have a car with no spare tire. We did get a puncture with a resulting slow leak while far from home. I took the tire off of the car, found and pulled out the puncturing object and inserted a rope plug to hold until we got home. If you do this, take note of the angle of the puncturing object so you can insert the rope plug in the same direction.

After arriving at home, the rope plug was removed and a mushroom plug was installed.

Be aware too that not all tire people will repair a puncture after the sealant has been used. I checked three places. Two would not; one would. If you can’t find someone to repair a tire with the sealant, you then get to buy a new tire. I am hoping that the lack of a spare tire will eventually be thought of as a bad idea that deserves to go away.

I was just comparing this to an incident I had ~2 yrs ago with my other car. Driving on the NJ Tpke, I had a tire blow out. After I pulled off the hwy, I found the sidewall had a hole in it large enough to put my fist thru. (Don’t think a compressor w/ sealer would have helped here.) This car had a compact spare, which I installed and was back on the road in ~15 min and reached my destination, about an hour away w/o further incident. The next morning, I drove to a tire store to buy a replacement tire. This was all done with a minimum of impact to my travel plans. What would have happened if I was stuck on the NJ Tpke, late at night, far from home, with NO SPARE?

Which tires do you have? Are they the run-flat variety or are they real tires?

Spare tires are disappearing for 2 reasons:

  1. They cost a lot. The manufacturer can reduce the price by up to $350 on a CTS by leaving it out. The compressor is not nearly that expensive. This also gives them another option for increasing profit margin. A couple hundred bucks doesn’t sound like much compared to a $40,000 car, but it adds up.

  2. It saves weight, and this translates into better fuel economy.

I agree that a spare tire, even a compact spare: (1) Takes up valuable space; (2) Adds cost to the base price; (3) Adds weight which reduces fuel economy – all bad things. Nevertheless, getting stuck by the side of the road in who knows where doesn’t sound like a good option either. If I can confirm that the car can be driven safely with a compact spare, I’ll look to obtain one.

“The manufacturer can reduce the price by up to $350 on a CTS by leaving it out”

$350 for a spare tire?
Instead of steel belts, do they use tires with platinum belts on these cars?

But, to return to the OP’s question–The reason why there is a well for a donut spare on this car is most likely related to the fact that this vehicle can be ordered with either AWD or RWD. I think it is likely that the RWD versions do have a spare tire, and that it is deleted on the AWD version in order to avoid mechanical problems resulting from owners driving long distances on a temporal spare.

If I were the OP, I would phone Cadillac customer service at the corporate level, in order to find out whether a donut spare can be used. If GM runs their customer service hotline like Toyota does, the phone person will refer the question to an engineer–assuming that their customer service manual does not provide the answer to this question.

I would go to a junkyard, but a donut spare tire that fits and put it in the space just in case and otherwise pretend it is not there! It is not like you will be using that space anyway. And flats seem a lot less common than they used to be.

I think there is a point that many folks are missing: joedcorn’s Cadillac is AWD! That changes the whole picture about what is acceptable for a spare.

Like he said, I also suspect that the minispare was deliberately replaced by the compressor to prevent driving on odd sized tires and damaging the drivetrain. Calling Cadillac is the right move, but I’ll bet a dollar for a donut (pun intended!) that everyone there says no dice to the minispare.

Definitely check with Caddilac about spare and AWD.

On my previous Subaru WRX there were incidents of the rear differential(limited slip) actually catching fire using the spare. I think I know why. My spare was woefully underflated (20psi instead of 50-60psi or whatever). I drove home with my 1.5 yr old and my WRX started clunking in the rear. I did not realize the tire pressure until day time and noticed the donut spare was saggy.

joedcorn can still buy a new rim and matching tire to create a full size spare. I imagine it will be acceptable for short distances after the tires wear. It’s a question of whether you are willing to lose a lot of trunk space. It would probably be a good idea to secure it so that it doesn’t move while you are driving.

Thanks for all the comments above. I always figured I could obtain a full size wheel (17") and tire to make up a full-sized spare. The problem is that it’s a pretty big tire (P235-55/R-17) that clearly would not fit in the well that’s only large enough for a compact spare, and thus would need to be carried in my trunk. It would essentially fill the entire trunk, leaving room for little else. My main reason for carrying a spare is when I’m traveling far from home, and that’s when I’d likely be carrying suitcases in my trunk. Clearly it could not accommodate both. I hope to get a clear answer from Cadillac on whether or not the compact spare creates handling and drive-train problems, given the car is AWD. andrew’s comment above with his Subaru experinece is enlightening.

One question that was hinted at but not answered, are your tires the “run flat” type? You could get by with out a spare if they are.

If they are not, and your current tires are near the replacement time, would you consider run flat tires as replacement tires? Consider the cost of 4 run flats with TPMS against the cost of 5 regular tires plus a new rim plus the loss of trunk space.

Run flat tires are not available in your size, but they are available in 225-60/17 and 245-50/17. These may require special rims though, you would have to check that out.

To answer some comments above, my tires are not “run-flat” but standard tires. Overall, I’ve heard more bad things than good about run-flat tires, including: (1) Expensive; (2) Take special wheels; (3) Wheels are much more prone to damage from road hazards, such as pot holes; (4) Much harsher ride; (5) If a tire fails, probably looking at having to replace ALL 4 TIRES. So even if they were available, I would not use “run flat” tires on this car. Thanks for all of the good advice and comments above. I still need to get info from Cadillac on whether this car will perform with a compact spare, although it’s looking more and more like it won’t, which is the reason they provide the compressor. BTW, the owner’s manual inducates that some Caddy’s DO come with a spare tire – I suspect those are for those cars that are RWD. (The CTS is available in a stickshift, which is RWD.)